tools/perf/util/trigger.h

   1 #ifndef __TRIGGER_H_
   2 #define __TRIGGER_H_ 1
   3
   4 #include "util/debug.h"
   5 #include "asm/bug.h"
   6
   7 /*
   8  * Use trigger to model operations which need to be executed when
   9  * an event (a signal, for example) is observed.
  10  *
  11  * States and transits:
  12  *
  13  *
  14  *  OFF--(on)--> READY --(hit)--> HIT
  15  *                 ^               |
  16  *                 |            (ready)
  17  *                 |               |
  18  *                  \_____________/
  19  *
  20  * is_hit and is_ready are two key functions to query the state of
  21  * a trigger. is_hit means the event already happen; is_ready means the
  22  * trigger is waiting for the event.
  23  */
  24
  25 struct trigger {
  26         volatile enum {
  27                 TRIGGER_ERROR           = -2,
  28                 TRIGGER_OFF             = -1,
  29                 TRIGGER_READY           = 0,
  30                 TRIGGER_HIT             = 1,
  31         } state;
  32         const char *name;
  33 };
  34
  35 #define TRIGGER_WARN_ONCE(t, exp) \
  36         WARN_ONCE(t->state != exp, "trigger '%s' state transist error: %d in %s()\n", \
  37                   t->name, t->state, __func__)
  38
  39 static inline bool trigger_is_available(struct trigger *t)
  40 {
  41         return t->state >= 0;
  42 }
  43
  44 static inline bool trigger_is_error(struct trigger *t)
  45 {
  46         return t->state <= TRIGGER_ERROR;
  47 }
  48
  49 static inline void trigger_on(struct trigger *t)
  50 {
  51         TRIGGER_WARN_ONCE(t, TRIGGER_OFF);
  52         t->state = TRIGGER_READY;
  53 }
  54
  55 static inline void trigger_ready(struct trigger *t)
  56 {
  57         if (!trigger_is_available(t))
  58                 return;
  59         t->state = TRIGGER_READY;
  60 }
  61
  62 static inline void trigger_hit(struct trigger *t)
  63 {
  64         if (!trigger_is_available(t))
  65                 return;
  66         TRIGGER_WARN_ONCE(t, TRIGGER_READY);
  67         t->state = TRIGGER_HIT;
  68 }
  69
  70 static inline void trigger_off(struct trigger *t)
  71 {
  72         if (!trigger_is_available(t))
  73                 return;
  74         t->state = TRIGGER_OFF;
  75 }
  76
  77 static inline void trigger_error(struct trigger *t)
  78 {
  79         t->state = TRIGGER_ERROR;
  80 }
  81
  82 static inline bool trigger_is_ready(struct trigger *t)
  83 {
  84         return t->state == TRIGGER_READY;
  85 }
  86
  87 static inline bool trigger_is_hit(struct trigger *t)
  88 {
  89         return t->state == TRIGGER_HIT;
  90 }
  91
  92 #define DEFINE_TRIGGER(n) \
  93 struct trigger n = {.state = TRIGGER_OFF, .name = #n}
  94 #endif